Move java examples

examples/java/MagicSquare.java

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+// Copyright 2011 Hakan Kjellerstrand hakank@gmail.com
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import java.io.*;
+import java.util.*;
+import java.text.*;
+
+import com.google.ortools.constraintsolver.DecisionBuilder;
+import com.google.ortools.constraintsolver.IntVar;
+import com.google.ortools.constraintsolver.Solver;
+
+public class MagicSquare {
+
+  static {
+    System.loadLibrary("jniortools");
+  }
+
+
+  /**
+   *
+   * Solves the Magic Square problem.
+   * See http://www.hakank.org/google_or_tools/magic_square.py
+   *
+   */
+  private static void solve(int n, int num) {
+
+    Solver solver = new Solver("MagicSquare");
+
+    System.out.println("n: " + n);
+
+    //
+    // variables
+    //
+    IntVar[][] x = new IntVar[n][n];
+
+    // for the branching
+    IntVar[] x_flat = new IntVar[n*n];
+
+    //
+    // constraints
+    //
+    final long s = (n * (n * n + 1)) / 2;
+    System.out.println("s: " + s);
+    // IntVar s = solver.makeIntVar(0, n*n*n, "s");
+
+    IntVar[] diag1 = new IntVar[n];
+    IntVar[] diag2 = new IntVar[n];
+    for(int i = 0; i < n; i++) {
+      IntVar[] row = new IntVar[n];
+      for(int j = 0; j < n; j++) {
+        x[i][j] = solver.makeIntVar(1, n * n, "x[" + i + "," + j + "]");
+        x_flat[i * n + j] = x[i][j];
+        row[j] = x[i][j];
+      }
+      // sum row to s
+      solver.addConstraint(solver.makeSumEquality(row, s));
+
+      diag1[i] = x[i][i];
+      diag2[i] = x[i][n - i - 1];
+    }
+    // sum diagonals to s
+    solver.addConstraint(solver.makeSumEquality(diag1, s));
+    solver.addConstraint(solver.makeSumEquality(diag2, s));
+
+    // sum columns to s
+    for(int j = 0; j < n; j++) {
+      IntVar[] col = new IntVar[n];
+      for(int i = 0; i < n; i++) {
+        col[i] = x[i][j];
+      }
+      solver.addConstraint(solver.makeSumEquality(col, s));
+    }
+
+    // all are different
+    solver.addConstraint(solver.makeAllDifferent(x_flat));
+
+    // symmetry breaking: upper left is 1
+    // solver.addConstraint(solver.makeEquality(x[0][0], 1));
+
+
+    //
+    // Solve
+    //
+    DecisionBuilder db = solver.makePhase(x_flat,
+                                          solver.CHOOSE_FIRST_UNBOUND,
+                                          solver.ASSIGN_CENTER_VALUE);
+    solver.newSearch(db);
+    int c = 0;
+    while (solver.nextSolution()) {
+      for(int i = 0; i < n; i++) {
+        for(int j = 0; j < n; j++) {
+          System.out.print(x[i][j].value() + " ");
+        }
+        System.out.println();
+      }
+      System.out.println();
+      c++;
+      if (num > 0 && c >= num) {
+        break;
+      }
+    }
+    solver.endSearch();
+
+    // Statistics
+    System.out.println();
+    System.out.println("Solutions: " + solver.solutions());
+    System.out.println("Failures: " + solver.failures());
+    System.out.println("Branches: " + solver.branches());
+    System.out.println("Wall time: " + solver.wallTime() + "ms");
+
+  }
+
+  public static void main(String[] args) throws Exception {
+    int n = 4;
+    int num = 0;
+
+    if (args.length > 0) {
+      n = Integer.parseInt(args[0]);
+    }
+
+    if (args.length > 1) {
+      num = Integer.parseInt(args[1]);
+    }
+
+    MagicSquare.solve(n, num);
+  }
+}